Dry cell



Nbv.- 17, 1936. R. R. SMITH DRY CELL Filed y 27, 1930 /6 /0 Y am/ HHHIHv my i W A? l in f W, INVENTOR/ I BY Q 63 z3i ATTORNEYS.

Patented Nova l7, 19 36 umreo stares PATENT orrice DRY CELL Ralph E.Smith, Fremont, Ohio, assignor, by

mesne assignments, to Union Carbide and Carhon Corporation, acorporation of New York Application May 27, 1930, Serial No. 456,172

34. Claims. (01. 136-133) This invention relates to dry cells andparticularly to improved means for closing and sealing such cells. Thepresent application is a continuation in part of my application SerialNo. 432,217

filed on February 28, 1930. g

In the manufacture of dry cells it has been common practice to close thecell by placing a layer of sand over the top of the mix body and thenpouring a layer of sealing compound, such as coal tar pitch or arosin-base sealing wax, over the sand. This type of closure is notaltogether satisfactory due to the manufacturing difficultiesexperienced in handling the compound and in applying it to the cells.The completed closure is also quite brittle when cold and, consequently,is easily broken during handling and shipment; it becomes quite plasticwhen subjected to relatively high summer temperatures; and bulges or isforced from its proper location by internal gas m pressure.

Another objection to this type of closure is that it must be madecomparatively thick in order to obtain the required strength, and thisreduces cell space and electrode area which otherwise 5, might beemployed to increase the capacity of the cell.

Another objection to this type of closure is that the area of the gasvent is capricious and not subject to manufacturing control. In drycells having this type of closure the gas generated within the cell isvented through the joint between the sealing compound and the zinccontainer or electrode. The fact that this joint is not tight and thatthe cell gas is vented through as it is largely accidental and, as aconsequence, the vent varies in size according to variations inconditions not readily controlled. As a result, the size of the vent istoo large in some 'cells and too small in others, and in the majority ofcases it so is effective for only a limited range of service conditions.

Therefore, some of the objects of this invention are to provide animproved closure or seal for dry cells which takes up very little of the45 valuable space within the cell; is neat in appearance; low in cost;easy to manufacture and apply; uniform and efiective to vent gas fromthe cell; and avoids various objections encountered in the use of waxand other types of closures.

50 These and other objects and the novel features of this invention willbe apparent from the following description and the accompanying drawing,in which:

Figs. 1- and 2 are enlarged vertical sectional 55 views of the top endof a dry cell showing the improved closure in place before and after thecell is sealed, and

Figs. 3 and 4 are, respectively, enlarged sectional and top views of adry cell having a modified closure embodying this invention.

The improved closure may have a variety of forms according to the sizeand shape of the cell, its interior structure, and the use for which itis intended. As shown in Figs. 1 and 2. of the drawing, the improvedclosure comprises an annular 10 sealing member or cover ill that isrelatively hard and resilient in comparison with the annular washer orseat it, formed for example from a relatively thin resilient metal, suchas sheet steel from about .010 to .030 inch thick, having an upturnedflange 5 l at its outer edge fitting snugly within the upper rim of thezinc container, can or cup l2, which rim is turned down over the flange.The cover preferably has a downturned flange it at its inner edgeadapted to press 29 tightly against an annular insulating seat it thatis relatively soft and yielding in comparison with the cover It, forexample, a washer of paper, rubber, fiber, or similar material, mountedon the upper end of the central carbon electrode i5.

The downturned fiangemay have a sharp edge adapted to embed in thewasher I l, as shown in Figure 2. A metal dowel l6, embedded in andextending upward from the center of the electrode l5, projects throughan opening in the $0 washer M and serves as the central circuit terminalof the cell.

The-inner and outer surfaces of the cover it are preferably coated witha layer or body of enamel, varnish, lacquer, or similar material 5 whichadheres to and insulates such surfaces and protects them from corrosion.The joint between the closure l0 and the container l2 may be furthersealed with asphalt paint, rubber cement, or similar plasticcomposition; and the joint between the g top of the electrode l5 and thebottom of the insulating washer l4 may be sealed with a similar plasticcomposition. However, a sealing composition in either of these joints isnot essential to the successful operation of the improved cell andclosure.

When the coverlfl is secured in place it is pressed into effectivesealing contact with the washer M in order to insure a fluid-tight jointbetween the cover, the washer, and the carbon 5 electrode. This pressureis preferably provided by deforming the cover I!) during the finalassembling operation. Prior to this operation the downturned flange I3is resting on the washer l4 and the upper edge of the upturned flange His substantially flush with the top of the can l2 as shown in Fig. 1.The final assembling operation consists in rolling or crimping the upperedge of the can i2 inward and then down over the u p turned flange ll,thus rigidly and permanently securing the outer edge of the cover to thecontainer. In performing this operation the outer edge of the cover ispreferably depressed so that the cover is dished and exerts somedownward pressure 'on the washer [4.

It is obvious that the jointformedbetween the flange i3 and the seat orwasher M is of such a nature that, while gas-tight at ordinarypressures, it is adapted to open and allow the escape of any gas thataccumulates to produce a pressure suflicient to overcome the resilienceof the cover I0; While this method of venting alone serves well in somecases, it is usually desirable that it be supplemented by the provisionof. another vent to operate at relatively lower pressure and of a morefixed nature.

The resulting .combination is particularly eflicient from the standpointof cell quality, since any venting system must be a compromise betweenexcessive loss of moisture from the cell and the accumulation of highgas pressures. In the present case the low pressure vent may be placedat a relatively lower capacity value than otherwise, since it must careonly for normal operating conditions. This yields minimum loss ofmoisture from the cell, since the high pressure vent is normally closedand operates only under abnormal conditions such as, for example, may beintroduced by excessive temperatures, or whenever abnormal quantities ofgas are produced, causingexcessive pressures within the cell.

It is practical to control the character of the venting valve providedby the washer I4 and the flange I3; and the pressure necessary to openit, by the regulation of several factors. The primary, factor is thenature of the insulating. washer, and the second is control of thepressure that the flange l3 exerts upon the washer by varying thedistance that the outer edge of the cover is depressed during thesealing and assembling operation, or by varying the thickness orresiliency of the cover material.

While the washer itself may in some cases form a practical low pressurevent by using suitable material, such as oil-treated pulpboard, that isimpervious to moisture but pervious to gas under the mechanical pressuresustained, it usually is preferable to'use a carbon electrode that issufficiently porous to vent the gas that normally occurs. A particularadvantage of the latter procedure is that it facilitates the escape ofgas generated in the lower regions of the. cell. In such a case theelectrode may be partially impregnated with a watererepellent substancesuch as lubricating oil or paraflin to yield the desired ventingcharacteristics. It is then preferable to use an impervious seat orwasher such as rubber, fiber or more cheaply a washer made from abibulous material such as pulpboard thoroughly impregnated with awater-repellent mixture composed of 50 per cent rosin and 50 per centparaflin by weight. I

In six inch cells of the construction shown in Figures 1 and 2 suitableelectrode impregnation covers a wide range according to the type of mixand paste used. At least one-tenth of the voids normally occurring inthe carbon electrode are ordinarily filled with water-repellentimpregnating material. More frequently the electrode impregnation ishigher and may be such as to fill half the voids or even more. In thiscase an impregnated pulpboard washer as described above, and about .04inch thick is suitable. Under these conditions the normal preferredpractice to obtain suitable flange pressure upon the washer is todepress the outer edge of the cover about inch during the assembling andsealing operation.

It is obvious that the conditions for this control' will vary accordingto the materials selected, the purposes in view, and the type and sizeof cell, but it has been found that practical control can be readilyachieved. This is true over a. practical range oftolerances with respectto relative positions of the top of the can and the top of theelectrode. The ability of the construction to accommodate itself tovariations of this nature represents a point of very important practicalvalue from a manufacturing viewpoint.

On some types of dry cells, such as the sizes for flashlights, it isadvantageous to use the modified form of closure shown in Figs. 3 and 4,which embodies the principles of this invention and differs only in afew details from the construction shown in Figs. 1 and 2. In Figs. 3 and4, the annular sheet metal closure I!) has a downturned flange 18 at itsouter edge and is bent downwardly within this flange, as at l9, so thata groove 20 is formed at the outer edge of the closure. The upper end ofthe zinc container I2 is crimped into the groove 20 and these parts maybe slightly inclined outwardly and upwardly, as shown, the closure beingthus permanently secured to the container bya substantially gas-tightjoint. The washer I4 is carried by the carbon electrode l5, beingsupported thereon by an outturned annular flange 2| at the lower edge ofa metal cap 22 which fits the upper end of the electrode. The capprojects outwardly..through the central opening in the washer and servesas the central circuit terminal ofthe cell. The top of the cap 22 ispreferably provided with one or more openings, such as the slits 23,through which gas may escape after passing through the carbon electrode.A disk 24 of paperboard may snugly fit the outside of the electrode andthe inside of the can in the space above the active material, sometimesdesignated as a cartridge, i. e., the mix body and the electrolyte, toprevent expanding electrolyte from contacting with the metal flange 2|.In all other features the cell and closure shown in'Figs. 3 and 4 mayembody the same construction and operation as the one shown in Figs. 1and 2.

It is also within the scope of this invention to vary the form of thecentral venting valve by omitting the flange I3, and by providing a.flange or ridge on the upper side of the insulating washer I4 to makecontact with a flat surface at the inner edge of the closure l0. Also,the

outer edge of the closure I may be secured to I claim:

1. In a dry cell; the combination of means for venting the amount of gasnormally generated therein without loss of a substantial amount ofmoisture; with means for venting abnormal amounts of gas to prevent thepressure thereof from injuring said cell.

2. In a dry cell; the combination of means for equalizing gas pressurein said cell and for venting the amount of gas normally generatedtherein without loss of a substantial amount of moisture; with meansfor. venting abnormal amounts of gas to prevent the pressure thereoffrom injuring said cell.

3. In adry cell wherein gas is generated at a varying rate during theoperation of the cell, the combination of means whereby such gas isvented at a rate materially below the maximum rate of gas generation inthe cell, to conserve the cell moisture and limit injurious effects forbreathing; and means whereby additional gas is vented when the rate ofgeneration exceeds the venting rate of the first mentioned means.

4. In a dry cell having a can; a carbon electrode in said can; a washeron said electrode having an opening; and a metal cover sealed to saidcan and having an opening therein with the edge thereof resting on saidwasher; the combination of means for venting a normal amount of cell gasthrough said electrode and the opening in said washer, with means forventing an abnormal amount of cell gas around said electrode through theopening in said cover.

5. A dry cell comprising a zinc container, a carbon electrode therein, arelatively soft and yielding insulating washer carried by saidelectrode, and a relatively hard and resilient'annular closure havingits outer edge permanently secured to the upper end of said containerand its inner edge contacting with said washer yet free to flex upwardlyto vent gas from the cell.

6. A dry cell according to claim 5 in which the carbon electrode issufliciently porous to vent gas from the cell and has a portion thereofexposed to the outer atmosphere.

'7. A dry cell comprising a container, an electrode therein, a washer ofa relatively soft and yielding porous material carried by said electrodewith a portion thereof exposed to the outer atmosphere, and a relativelyhard and resilient annular impervious closure having its outer edgepermanently secured to the upper end of said container and its inneredge contacting with said washer yet free to flex upwardly to vent gasfrom the cell.

8. A dry cell comprising a zinc container, a carbon rod electrodetherein, a relatively soft and yielding insulating washer carried bysaid electrode, and an annular resilient sheet metal closure having itsouter edge permanently secured to the upper end of said container andhaving its inner edge turned downwardly, said closure being so deformedthat its inner edge presses tightly against said washer.

9. A dry cell comprising a container, an electrode therein and having a"portion thereof exposed to the outer atmosphere, said electrode beingsufficiently porous to vent gas from the cell at a rate below themaximum rate of gas generation in the cell while preventing the escapeof moisture, a seat on said electrode, and a resilient annular closurefor said container, said closure having its outer edge permanentlysecured to the upper end of said container and its inner edge contactingwith said seat yet free to flex upwardly to vent gas from the cell at arate greater than the electrode.

10. A'dry cell comprising a container, a porous electrode thereinnormally adapted to vent gas from said cell and having a portion thereofexposed to the outer atmosphere, a relatively soft and yielding washercarried by said electrode, and a relatively hard and resilient annularclosure for said container, said closure having its outer edgepermanently secured to the upper end of said container by asubstantially gas-tight joint and having its inner edge pressing againstsaid washer but separable therefrom to release excessive gas pressure insaid cell.

11. A dry cell comprising a zinc container; a porous carbon electrodetherein having a portion thereof exposed to the outer atmosphere andnormally adapted to vent gas from said cell; a relatively soft andyielding insulating disk carried by said electrode; and an annularresilient sheet metal cover having its outer edge permanently secured tothe upper end of said container by a gas-tight joint and having itsinner edge contacting with said disk but free to separate therefrom torelease abnormal gas pressure in said cell.

12. A dry cell comprising a container, an electrode therein carrying ametal circuit terminal, a relatively soft and yielding disk mounted onsaid electrode and having an opening through which said terminalprojects, and a relatively hard and resilient annular cover for saidcontainer, said cover having its outer edge permanently secured to theupper end of said container and its inner edge contacting with said diskyet free to flex upwardly to vent gas from the cell.

13. A dry cell comprising a metal container, a carbon electrode thereincarrying a metal circuit terminal,-an insulating disk mounted on saidelectrode and having a relatively soft and yielding opening throughwhich said terminal projects, and a relatively hard and resilientannular sheet metal cover for said container, said cover having itsouter edge permanently secured to the upper end of said container andits inner edge contacting with said disk yet free to flex upwardly tovent gas from the cell.

14. A dry cell comprising a zinc container, a porous carbon rodelectrode adapted to vent gas from said cell, a metal circuit terminalcarried by said electrode, an insulating disk mounted on said electrodeand having an opening through which said terminal projects, and anannular resilient sheet metal closure for said container, said closurehaving its outer edge permanently secured to the upper end of saidcontainer by a gas-tight joint and its inner edge turned downwardly,said closure being so deformed that said inner edge contacts with saidseat but is displaceable therefrom to release abnormal gas pressure inthe cell.

15. A dry cell comprising a container, an electrode therein, an annularclosure member in contact with said electrode, and an annular closuremember having its outer edge secured to the upper end of said container,one of said members being relatively hard and resilient and the other ofsaid members being relatively soft and yielding, said relatively hardand resilient memher having a free edge in contact, with the uppersurface of said relatively soft and yielding memher and being free toflex upwardly to vent gas from the cell.

.16. A dry cell as defined in claim 15 in which (iii i with said seat athe closure er a; in a carbon electrode e d or said electrode; etal eofattaches to it, a? langed down-we ti and sure in said cell tovent th- Ina dry cell having carbon electrode therein; a A yielding preformer'i osaid electrode; relatively container and the ther with a downtornedembedded Washer" 19. In a dry cell having a container with a carbonelectrode therein; a seat upon the upper end of said electrode; and anannular resilient metal sealing member having the outer edge thereofrigidly secured to said container and the inner edge thereof flangeddownward and termimating in a sharp edge embedded in said seat butadapted for being raised therefrom by gas pressure within said cell forventing the same.

20. In a dry cell having a container with a carbon electrode and anelectrolyte therein; a metal dowel extending upward from said electrode;a seat comprising a washer of material impervious to said electrolyteencircling said dowel and forming a joint 'with said electrode throughwhich said electrolyte will not pass; and an annular resilient sealingmember having an upturned flange at the outer edge thereof over whichthe upper edge of said container is crimped, and a downturned flange atthe inner edge thereof terminating in a sharp edge embedded in said seatbut adapated for being raised therefrom by gas pressure within said cellfor venting the same.

21. In a dry cell having a container with a flattopped carbon electrodetherein; a preformed fiat annular disc of bibulous material impregnatedwith waterproofing material on the fiat top of said electrode; and adished closure of resilient metal having the outer edge thereof rigidlysecured to said container so that the inner edge thereof exerts aresilient pressure on said disc, said cover being, free to raise fromsaid disc to vent excessive gases and to return to said disc to form 'atight seal.

22. In a dry cell having a container;.a gaspervious waterproof carbonelectrode in said container with a portion exposed to the outeratmosphere so that gas normally generated in said cell may escapetherethrough; an impervious bibu- .lous washer 0n the upper end of saidelectrode;

and a sealing member oi resilient metal secured under stress between theupper surface of said washer and the upper edge of said container sothat the pressure oi? '"iore gas than can escape through said electrodetill raise the sealing mem her and permit escape of gas between theinner edge thereof and said washer.

23. A dry cell comprising a zinc container, a carbon electrode thereinhaving a metal dowel projecting centrally from its upper end, arelatively soft and yielding dish mounted on said elec trode and havingan opening through which said dowel protects, and a relatively hard andresilient annular cover for said container, said cover having its outeredge permanently secured to claim nsl of ihe ilating sis-ts metal,

said

the cell, and projecting pa is slitted to expose a portion of saidelectrode to the outer atmosphere.

2?. in a dry cell, a metal cup, a cartridge within said cup, anelectrode arranged centrally or said cartridge, a resilient metal coverhaving a rigid gas-tight connection with said cup and having a centralopening, a metal cap mounted on said electrode and projecting throughsaid opening and having an annular shoulder, and an annular insulatorresting on said shoulder and underlying said cover, the inner edge ofsaid cover being turned at an angleto the remainder and pressed intosealing relation with said insulator by tension exerted solely by saidcover.

28. A dry cell comprising a container electrode; an electrode memberwithin and spaced from said container electrode; active material in thespace between such electrodes; a closure for the cell comprising a metalcover member supported by said electrode member and havirm a marginalportion secured to said container electrode; said container electrodeand said cover member consisting of dissimilar metals; and a coating ofinsulating material upon the interior surface of said cover member. g

29. A dry cell comprising a container electrode; an electrode memberwithin and spaced from said container electrode; active material in thespace between said' electrodes; a closure for the cell comprising anannular metal cover member hflV'? ing one margin thereof secured to saidcontainer electrode and having another margin thereof sup-: ported bysaid electrode member; said container electrode and said cover memberconsisting of dissimilar metals; and a layer of insulating materialadhering to and coating the interior surface of said cover member.

30. A dry cell comprising a metal container electrode; an electrodemember within spaced from said container electrode; active materialbetween said electrodes leaving a free space above said active material;a metal terminal can carried by said electrode member, said having aportion thereof within said freespace; an annular metal cover having itsinner ma? jacent to but insulated from said cap and "having its outermargin permanently secured to said con tainer electrode; and a coatingof-insulating material upon the interior surface of said cover.

Bl. A dry cell comprising a container electrode; an electrode memberwithin and spaced from said container electrode; active material in thespace between said electrodes; a closure for the cell com prising ametal cover member supported by said electrode member and having amarginal portion secured to said container electrode; said containerelectrode and said cover member consisting of dissimilar metals; andplastic material sealing the joint between said cover member and saidcontainer electrode.

32. A dry cell comprising a container electrode; an electrode memberwithin and spaced'from said container electrode; active material in thespace between said electrodes; a closure for the cell comprising a metalcover member having a portion supported by said electrode member andhaving a marginal portion secured to said'container electrode; saidcontainer electrode and said cover member consisting of dissimilarmetals; a surface coating of insulating and protective material upon theinterior surface of said cover member; and plastic. material sealing thejoint betweensaid cover member and said container electrode.

33. A dry cell comprising a container; an electrode therein; a washer ofa relatively soft and yielding porous material carried by said electrodewith a portion thereof exposed to the outer atmosphere, the said washerbeing impervious to moisture but pervious to gas under the pressuresdeveloped in the cell; and a relatively hard and resilient annularimpervious closure having its outer edge rigidly secured to the upperend of said container and its inner edge contacting the said washeryetfree to flex upwardly to vent gas from the cell.

34. A dry cell comprising a metal container; a carbon electrode therein;a metal cap mounted on the upper end of said 'electrode and having anout-turned flange; a relatively soft and yielding washer mounted on saidflange and having an opening through which said cap projects, the saidwasher being impervious to moisture but pervious to gas under pressuresdeveloped within the cell; and a relatively hard and resilient annularcover for said container, said cover having its outer edge permanentlysecured to the upper end of said container and its free inner edgecontacting with said washer yet free to flex upwardly to vent gas fromthe cell.

RALPH B. SMITH.

